The invention relates to a method, and an apparatus for carrying it out, for the temperature regulation of components, for example semiconductor circuits, printed circuit boards and the like, in which the components are conveyed on carriers through an inlet slot into a temperature-regulating housing provided with temperature-regulating members and are conveyed out through an outlet slot opposite the inlet slot.
An apparatus which operates according to this method is disclosed in DE-A 4020920. This apparatus is a continuous furnace for preheating workpieces that are to be fed for further processing. This continuous furnace contains two transport systems each configured after the manner of two paternosters which are arranged next to one another and contain circulating belts guided via an upper and a lower deflection roller. In this case, the direction of rotation of the deflection rollers is chosen such that the mutually facing strand sides of the circulating belts each run in the same direction, with the result that accommodating parts fitted to the circulating belts execute either an upwards movement or downwards movement in the region between two circulating belts. On account of the arrangement of two transport systems of this type one behind the other, that is to say with coaxial axes of the upper deflection rollers and lower deflection rollers, and a driving direction of the deflection rollers in one transport system opposite to the driving direction in the other transport system, the result is, for shaped metal sheets inserted into one transport system in each case and serving to carry the workpieces to be treated, that the said shaped metal sheets are transported upwards, transferred from the upwards-transporting transport system to the downwards-transporting transport system and are transported downwards in the latter transport system. In this case, the upwards-transporting transport system is loaded through an inlet slot, situated in its lower region, in the continuous furnace and the shaped metal sheets are discharged via an outlet slot in the lower end of the downwards-transporting transport system, the inlet and outlet slots lying opposite one another. To enable the transport via the two transport systems and from one transport system to the other to proceed without any disruptions, the movement of the transport systems is cyclically timed in the corresponding manner.
Furthermore, U.S. Pat. No. 5,158,224 discloses a heating housing for preheating circuit boards to be soldered, which heating housing uses a transport system after the manner of a transport system in the document discussed above. The circuit boards are inserted into the interior of the housing through a slot situated in the lower region of the temperature-regulating housing and, in the process, are gripped by the two opposite transporting belts of its single transport system, which then transports the circuit boards upwards until the latter reach the level of an outlet slot which is situated in the upper region of the housing and from which the circuit boards, which have been heated in the interior of the housing, are then discharged.
The invention is based on the object of simplifying the procedure of the method underlying the abovementioned continuous furnace. This is done according to the invention by virtue of the fact that the carriers are accommodated by a magazine in the housing, which magazine is provided with adjacently arranged holders and, after the first holder has been loaded, is displaced progressively in one direction from a starting position into successive accommodating positions in which the individual holders of the magazine are loaded one after the other, whereupon, after all the holders have been loaded, the magazine thus filled is displaced, from the end position that has been reached in the process, back to its starting position in a fast reverse run in the opposite direction, in which starting position a carrier is conveyed in through the inlet slot and, with the magazine having been filled, the first temperature-regulated carrier in the magazine is conveyed out through the outlet slot and, with the successive loading of the individual holders of the magazine, the individual temperature-regulated carriers are conveyed out successively, a temperature-regulated carrier being replaced by a non-temperature-regulated carrier and the residence time of the carriers in the magazine corresponding, identically for all of the carriers, to the period of time between two reverse runs, until all the holders of the magazine are loaded again in the end position reached by the said magazine, whereupon, after the reverse run of the magazine to the starting position, the magazine is progressively loaded again.
As this method proceeds, a back and forth movement, or up and down movement, is produced within the temperature-regulating housing without any deflections and without a transfer function having to be performed between the two directions of movement, a single simple displacement mechanism being required for the back and forth movement.
In this case, each carrier whose temperature is to be regulated is acted upon uniformly for a specific period of time, namely their residence time in the temperature-regulating housing, defined by the period of time between two reverse runs.
The displacement of the magazine in the temperature-regulating housing is advantageously effected in the vertical direction. This arrangement results in a relatively small installation area for the temperature-regulating housing, since the latter merely requires a vertical space in which a single up and down movement takes place. It is possible to configure this up and down movement from the starting position to the end position either from the bottom to the top or from the top to the bottom. Displacing the magazine from the starting position to the end position from the bottom to the top facilitates the fast return movement of the filled magazine from the end position back to the starting position, namely from the top to the bottom, since the force of gravity assists this fast movement.
It shall be pointed out, however, that the displacement of the magazine can also be effected in the horizontal direction if this appears to be necessary for the loading of the temperature-regulating housing and the unloading of the temperature-regulated carriers.
The apparatus for carrying out the method according to the invention is expediently configured in such a way that the temperature-regulating housing is approximately twice as long as the magazine and, in its central region, has the inlet slot and the outlet slot opposite, that the magazine is provided with a displacement mechanism for progressively displacing it into a position where its holders are in each case aligned with the inlet and outlet slots, and that the temperature-regulating housing has temperature-regulating members which bring the interior of the housing to a temperature that can be set in such a way that the components assume a desired temperature during the residence time.
This configuration results in an opening in the temperature-regulating housing for the inlet slot and the outlet slot approximately in the centre of the housing, which is favourable for the thermal balance of the temperature-regulating housing. Furthermore, the guidance of the magazine in the temperature-regulating housing requires merely a single displacement mechanism which acts in a straight line and effects the movement of the magazine both in the upwards direction and in the downwards direction. The temperature-regulating members accommodated in the housing ensure that, with consideration for the residence time of the components which is defined by the displacement mechanism, the temperature to be assumed by the components can be set without difficulty by means of an adjustable temperature of the temperature-regulating members.
The apparatus according to the invention can advantageously be used for heating printed circuit boards upstream of the melting zone of a soldering installation, the temperature-regulating members being formed by heaters. However, it is also possible to arrange the apparatus downstream of the melting zone of a soldering installation, for which purpose the temperature-regulating members may then be formed by coolers.
Since the apparatus is intrinsically a closed structure, it is possible to arrange a plurality of such apparatuses adjacently to one another and to connect their inlet and outlet slots to one another. This makes it possible to realize individual and step-by-step temperature regulation of components, in particular the curing of potting compositions in connection with semiconductor circuits.